Antibacklash driving mechanism

ABSTRACT

A DRIVING MECHANISM FOR ELIMINATING BACKLASH HAVING AN OUTPUT SHAFT WITH A FLAT SURFACE THEREON AND A ROCKER ARM HAVING A CENTER SECTION WITH A FLAT SURFACE ENGAGEABLE WITH THE FLAT SURFACE ON THE OUTPUT SHAFT AND FIRST AND SECOND END SECTIONS OF SAID ROCKER ARM AND FIRST AND SECOND MEANS FOR APPLYING ECCENTRIC FORCES, RESPECTIVELY, TO SAID FIRST AND SECOND END SECTIONS THEREBY PROVIDING A TORQUING FORCE TO POSITION SAID FLAT SURFACE OF SAID CENTER SECTION OF SAID ROCKER ARM IN DRIVING RELATION WITH SAID FLAT SURFACE ON SAID OUTPUT SHAFT.

Jan. '26, 1971 .R. J. ESTLICK 3,557,630

ANT IBACKLASH DRIVING MECHANISM Filed Marbh 24, 1969 2 Sheets-Sheefl INV E NTOR RAYMOND J ESTL/CK X M BY gangsta- M,

ATTORNEYS Jan. 26, 1971 R. J. ESTLICKI 3,557,630

ANTIBACKLASH DRIVING MECHANISM Filed March 24, 1969 2 Sheets-Sheet 2 FIG. 4

FIG. 6

Patented Jan. 26, 1971 United. States Patentbe 3,557,630

p p 2 z I 1 3,557,630 q g p are utilized to-rotate the driven member about its longi- Rayrnond rslsk llgnneoggy gliig It is therefore a general object of the present invention a asslgllm s" o, e; m ae o y g g g yi e y f the Navy, H I to provide a simple and relatively inexpensive device for ..t driving a member in two directions, that is clockwise, or

1 counterclockwise, without any loss of motion.

. .,Other objects and advantages of the present invention will be readily appreciated as the same becomes better I w v g understood by reference to the following detailed descrips. ABSTRACT-0F THE S L SURE tion when considered in connection with the accompany- A davingmehani'sm for eliminatingbacklash 1mm g; mg drawmgsan output shaft witha'fiat" 'surface thereori'and arocler' BRIEF DESCRIPTION OF THE DRAWINGS anm having acenter sectionwi th afiat surface engageable with the fiat surfac 0 the utput shaft and first and second end scti'ris of s'aid 'rdcke'r-i'armi ahd first and of the rocker S w- 5 ???f}'.. P Y l' FIG. 2 is a ffont view of the rocker arm shown in s -fi tianqf 99mm a d s h by Pwv d a FIG. 1 of the drawingstrqwn y s t9. Bastien sa d e} rf s t w se 1 .FIG. 3' is a sectional view taken on line 3 3 of FIG. 2; sectlon of sald {ocker m..- w e:r at on withdsatd FIG. 4 is a sectional view showing a preferred emflat Surface on 52nd l lfihfi ls i bodiment of the present invention;

V v e I FIG. 5 is a partial side view of the preferred embodiment; and

R. .N FIG. 6 is a partial sectional view showing a driving The present invention elates 01a driving mechanism and d l n member FIG. 1 is a top view of a rocker arm with push rods pi votally attached thereto and offset from the center and more particularly fo a drivingmechanism that elimi-i DESCRIPTION OF THE PREFERRED nates backlash between a driven load and a driving EMBODIMENT System Referrin fi g rst to FIGS. 4, 5, and 6 of the drawings,

Vanous Schemes and f l' have m the P l' there is shown a housing 11 which is mounted in bearings employed to reduce or ehmmate backlash m dnvmg 12 and 13 to rovide ali nment and a concentric h le mechanism. Most frequently gear trains are employed 14 is rovidedpin housing 11 out ut shaft lsois and various devices have been used to eliminate backlash. d h l 4 d P I h d One commonly employed antibacklash device is comrotata y mounte m 06 an a Semlclrcu ar 8 ape prised of a first narrow width gear fixedly attached to a g Is g i 3: fi z g g g g shaft, and a second narrow width gear rotatable on the S m 6 H rf g h same shaft and contiguous with the first gear. The first clrcular Shaped tang prov! es a at ace 7 on t e and second gears are resiliently biased together by means ig fi %g::? fia gzz gi i zg ag ggz of pins and coil springs and are normally engaged with d f a third gear equal in width to the combined widths of shown) w m are utlvlze or ulgamlssl the first and second gears. This commonly employed A rocker arm havulg a cylmdnFal Scene 19 *E device, often called a split gear train, performs very satisg i g g i fg 1 ig g 5 123;

factorily in operation in reducing or eliminating backz i s drawin S c drical Section 19 lash, but has a main disadvantage in that a large number g y of parts are required, some devices reqniring as many a z 2 g p 3 the f g l near gg as fifteen arts to akeu asin 1e assembl en an an are P95110116. m grooves.

i antikbgklashpdevicg is Showny and described and 25, respectively, to seal against moisture and dirt.

- Cylindrical section 19 of rocker arm 18 has a relief 28 as first spur gear integrally attached to a tubular shaft with g i g g gg gzrg fi z l gg g jgg gg fiz g g g a second spur gear having the same diametral pitch and t the same number of teeth, integrally attached to a second z fig tfgfi gg izjg g g gl g gf ii 2353??? h ft. Th second shaft is ositioned within the bore if the tub iilar shaft and the e iids of these shafts opposite of tang 16 ellgages flat Surface 29 on y f fi the ends the gears are attached are pinned together. The ig g g j gi i z g 2x3 2 3 gg g 22252225232; amers 22.51; mars: to 31 by 36. Bearin s 37 and '38 are rovided to facilitate pivotto engagl'ngamatmg gear ing. As best seen in FIGS. l and 5 of the drawings, the center line 41 of cylindrical section 19 is offset a distance SUMMARY OF THE INVENTION d from the center line 42 of push rods 34: and 35. Push The present i ti relates t a dri i mechanism rods 34 and 35 are actuated by hydraulic linear actuators which does not have any gears and in which a driving 43 and p wfi ymember engages and can drive a driven member without The engagementipf P rods 34 and 35 Wlth y f any loss of motion. The driven member, which might be 32 l'espectlvely, Such that forces are PP a shaft, is provided with a flat surface and a rocker arm Perform two functlonspusl'lfods 34 and P is provided with a mating flat surface which engages Vlde the force necessary to P P l p Shaft 15 the flat surface on the driven member. The rocker arm and in addition, forces are PP Which remove all is provided with first and second end sections, and ecbacklash between rocker arm the and Sha t centric forces are applied to these end sections which prothe'dfiverl element f forces are pp at POlIltS vides a torquing force to keep the flat surface on the eccentric to the center axis of rocker arm 18, the offset rocker arm in positive engagement with the flat surface being dis a and this Offset Causes rocker rm 18 on the driven member and also these eccentric forces to be rotated about its center so that the flat surface 29 of cylindrical section 19 engages the-fiat surface .17 on tang 16 of output shaft 15. Driving forces are transmitted through the fiat surface engagement. This engagement force is always the sum of the two forces applied by the push rods and effectively removes all backlash.

It can thus be seen from the foregoing description that the present invention utilizes a driving force to perform a second function of removing backlash. There is no development of backlash due to wear as the mechanism will automatically adjust itself. The present invention provides for the indexing of an output shaft, with its load, by the simple and inexpensive expedient of machining a fiat surface on the end of a shaft.

I claim:

il. An antibacklash device comprising:

a housing,

an output shaft rotatably positioned in said housing and having a flat surface on one end thereof,

a rocker arm having first and second forked end sections and a cylindrical center section having a relief therein extending to the longitudinal axis thereof thereby providing a flat diametrical surface engageable with said flat surface on said output shaft, the centers of said forked end sections being offset from the longitudinal axis of said cylindrical cen ter section, and V first and second means for applying forces, respec tively, to said first and second forked end sections whereby 'a' torquing force is developed to position said flat surface of said "center section of said rocker arm in driving relation with said flat surface on said outputshaft and whereby said first and second I means selectively [apply forces for pivoting said rocker'arm thereby turning said output shaft. '2. An antibacklash device as set forth in claim 4 wherein said .cylindrical center section has a tapered surface conterminous with said flat surface whereby the lengthof said fiat surface is less than the diameter of said cylindrical center. section. 7

3. A zero backlash device as set forth in claim 4 r wherein said. first andlse'cond means comprises piston- 7/1951 2,782,863" 2/1957 Christy et 1.' 74.-589 3,166,952 1/1965 Lang 74 440 2,868,033 1/1959 Gaither. 2,881,799 4/1959 Menewisch.

FRED c. MA'I'IERN, inf Primary Examiner W. S. RATLIFF, IR. Assistant Examiner g US. Cl. X.RL 744.40

P0405) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION UNDER RULE 322 Pa en 3,557,630 Dated January 26, 1971 Inventor) R. J. ESTLICK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, Claim 2, change:

"An antibacklash device as set forth in claim 4" To read:

An antibacklash device as set forth in claim 1 Column 4, Claim 3, change:

"A zero backlash device as set forth in claim 4" To read:

A zero backlash device as set forth in claim 1 Signed and sealed this 2nd day of November 1 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents 

